1. Field of the Invention
The present invention relates to computer keyboards and more particularly, to a self-illumination circuit board for computer keyboard. The invention relates also to a self-illumination keyboard using such a self-illumination circuit board.
2. Description of the Related Art
Following fast development of computer-related technology, many practical and functional electronic products have been continuously created and have appeared on the market. Most commercial electronic products have an input device made in the form of a mouse, keyboard, joystick or light gun for data or command entry. For different applications, different computer keyboards shall be used. For example, a keyboard for notebook computer is quite different from the configuration of a keyboard for desk computer. A notebook computer has light, thin, short and small characteristics. Therefore, the key switch structure of a keyboard for desk computer cannot be directly used in a keyboard for notebook computer. It must be specially configured to fit the requirements for notebook computer.
A conventional key switch structure for computer keyboard has a linking mechanism provided between a key cap and a bottom board to support vertical movement of the key cap. The linking mechanism may be made in the form of a cross-linkage (scissors-structure), rotary shaft structure or sliding structure. FIG. 13 illustrates an illuminated keyboard structure according to the prior art. According to this design, the illuminated keyboard comprises a key switch unit A and a backlight unit B. The key switch unit A includes a bottom board A1, a circuit board A2 supported on the bottom board A1 and carrying a light emitting device A21, a membrane A3 located on the top side of the circuit board A2 and carrying a light transmission rubber cone A31, a key cap A5, and a linking mechanism A4 coupled between the bottom board A1 and the key cap A5 around the rubber cone A31.
The backlight unit B includes a light guide board B1 provided at the bottom side of the bottom board A1, and a reflector B2 located on the bottom side of the light guide board B1.
The light emitting device A21 emits light toward the bottom side. The reflector B2 reflects light from the light guide board B1 toward the key switch unit A to light up the key cap A5. Therefore, a user can see the key cap A5 clearly when it is dark.
The aforesaid illuminated keyboard structure is functional, however it still has drawbacks as follows:
1. The light emitted from the light emitting device A21 at the circuit board A2 is projected onto the key cap A5 after through multiple reflection and refraction actions, resulting in energy loss. Thus, the illumination at the key cap A5 is weak.
2. The arrangement of the backlight unit B greatly increases the height of the keyboard structure, thus the keyboard structure is not suitable for use in an electronic product having light, thin, short and small characteristics.
3. The bottom board A1 has support members inserted through respective openings on the circuit board A2 and respective openings on the membrane A3 for the connection of the linking mechanism A4. The presence of the openings on the circuit board A2 limits the design of the circuit layout on the circuit board A2 and complicates the fabrication of the circuit board A2.
4. The key switch unit A can be made having pressure pads to substitute for the arrangement of the circuit board A2, membrane A3, linking mechanism A4 and key cap A5. However, the installation of the pressure pads and arrangement of circuits in the pressure pads are complicated, and the relative manufacturing cost is high.
Therefore, it is desirable to provide a self-illumination circuit board/keyboard that eliminates the aforesaid drawbacks.